A light emitting diode refers to an element in which minority carriers (electrons or holes) injected using a p-n junction structure of a semiconductor are produced and certain light is emitted through recombination thereof. Such light emitting diodes have been used as display devices and backlights, and studies on application of the light emitting diodes to general illumination have been actively conducted.
This is because light emitting diodes have less electric power consumption and longer lifespan as compared with existing bulbs or fluorescent lamps. That is, this is because the electric power consumption of light emitting diodes is only one severalth to one several tenth, and the lifespan thereof is several to several ten times as compared with existing illuminators, thereby achieving reduced electric power consumption and excellent durability.
Generally, to use a light emitting diode for the purpose of illumination, light emitting elements are formed through a separate packaging process, the plurality of light emitting elements are connected in series by means of wire bonding, and a protection circuit, an alternate current/direct current (AC/DC) converter and the like are installed at the outside of the light emitting elements so that the light emitting diode can be manufactured in the form of a lamp.
FIG. 1 is a conceptual diagram illustrating a conventional light emitting device. Referring to FIG. 1, a light emitting device for general illumination is manufactured by serially connecting a plurality of light emitting elements 10a to 10c each of which has a light emitting chip mounted thereon. To this end, the plurality of light emitting elements 10a to 10c are arrayed in series, and the light emitting chips within the different light emitting elements are electrically connected in series through a metal wiring process. Such a manufacturing process is disclosed in U.S. Pat. No. 5,463,280. However, if a light emitting device for general illumination having the aforementioned structure is manufactured according to the prior art, there is a problem in that the metal wiring process should be performed for a large number of elements one by one so that processing steps increase in number and are complicated. As the number of the process steps increases, a fraction defective also increases, thereby impeding mass production. Further, there may be a case where metal wiring becomes a short circuit due to a certain shock so that the operations of light emitting elements are stopped. Furthermore, there is a disadvantage in that spaces occupied due to serial array of respective light emitting elements are expanded so that the size of a lamp considerably becomes large.
An array of microchips at a wafer level rather than the array of light emitting chips at an element level described above is disclosed Korean Patent Laid-Open Publication No. 2004-9818. This relates to a display apparatus, wherein light emitting cells are arrayed in a matrix form such that a light emitting diode for inducing luminescence is disposed in each pixel. However, different electric signals should be applied in respective vertical and horizontal directions and the electric signals should be supplied in an address manner so as to cause the elements arranged in the matrix form to emit light, which is very difficult to control. Further, wiring may be disconnected due to the array in the form of a matrix, and a great deal of interference occurs in wire-overlapping areas. Furthermore, there is a problem in that the aforementioned matrix-shaped structure is not applicable to a light emitting device for illumination to which a high voltage is applied.